retroperitoneal ancient schwannoma: a very rare case report

Background: ancient schwannoma is an uncommon neoplasm originating from the peripheral nerve sheaths. ancient schwannoma occurs mostly in head and neck region and its occurrence is very rare in retroperitoneal (about 0.7% to 2.6% of all schwannomas), and despite its benign nature, it can show malignant behaviors and it may be misdiagnosed with sarcomas in some cases. there is nonspecific clinical symptoms and radiologic findings. evaluation of histology and immunochemistry is necessary for diagnosis, and complete surgical resection is the treatment of choice for schwannoma. case report: we report a unique case of retroperitoneal ancient schwannoma in a 50-year-old man with complaint of severe pain in the right flank area for 3 days ago, which was diagnosed with ancient schwannoma after evaluation of the histopathologic and immunohistochemical findings. after surgery, the patient was kept under regular follow-up since last 15 months without any evidence of recurrence.